Processing/Time Limits for Appeal. In the event a grievance is unresolved after being processed through all of the steps of the Grievance Procedure, unless mutually waived or having passed through the various steps by timely default of the Employer, then within fifteen (15) days after the rendering of the decision at Step 2 or a timely default by the Employer at Step 2, the aggrieved party may submit the grievance to arbitration. Within this fifteen (15) day period, the parties will meet to attempt to mutually agree upon an arbitrator. Should the parties be unable to agree, a list will be obtained per Section 2.